Conventional artificial lung/gas exchanger/oxygenators include at least a body, often defining a cylinder, a blood inlet, one or more blood outlets, and a gas (oxygen) supply inlet and outlet. The interior of such devices includes a plurality of hollow membrane fibers whose porosity allows passage of gases such as oxygen and CO2, but not of liquid, blood cells, blood proteins, etc. Gas inflow/outflow ports are provided, typically in fluid communication with one another via the lumens of the hollow membrane fibers, Using one or more pumps or potentially the patient's own heart pumping action, blood flow is established whereby oxygen-depleted and CO2-enriched blood is removed from a patient's bloodstream, passes into the device via the blood inlet, passes over exterior surfaces of the hollow membrane fibers, and exits the device through the blood outlet. During this traversal, oxygen passes from the hollow fiber lumens into the blood, and CO2 is removed from the blood and passes into the hollow fiber lumens to be removed by a sweep gas. From there, the oxygenated blood is returned to the patients bloodstream. It is for that reason that such devices are often termed “artificial lungs,” for their ability to replace or supplement the gas exchange function of the patient's own lungs.
Disadvantageously, conventional artificial lungs often provide uneven blood perfusion. This is because existing such devices typically include areas wherein blood flow becomes lessened or even stagnant. This causes thrombosis and in extreme cases device failure. In turn, a traditional artificial lung circuit consists of an oxygenator/artificial lung as described for gas exchange/oxygenation, a double lumen cannula or two separate cannulas for blood infusion/drainage into/from a patient, and a blood pump to drive the blood through the circuit. In a typical pneumatically driven pump, each pumping cycle includes a systolic phase (pushing blood from a pump blood chamber into a patient through an infusion cannula lumen) and a diastolic phrase (withdrawing blood from the patient into the pump blood chamber through a drainage cannula lumen). The systolic and diastolic phases of the pumping cycle are performed alternately, not simultaneously. Therefore, the infusion/drainage cannulae can only move blood during 50% of the pumping cycle. This requires twice the blood flow rate and twice the driven pressure/delta p to move the same amount of blood compared to a pump cycle where the systolic and diastolic phases could be performed simultaneously. For this reason, a relatively larger-sized cannula is needed to move the same amount of blood as would be possible if the cannulae could move blood for a greater percentage of the pumping cycle, which is disadvantageous in situations requiring peripheral cannulation, since the cannula size is strictly limited by the size of the blood vessel to be cannulated.
To solve this and other problems, the present disclosure provides a compact hollow fiber membrane blood oxygenator including an integral pneumatic pump and blood flow redirector structures, eliminating the need for a separate pump and so simplifying the artificial lung circuit. The present disclosure also provides such an oxygenator including an additional pneumatic pump serving as an atrium, to the oxygenator pump inlet, allowing withdrawal from and pumping blood to a patient to occur simultaneously, increasing efficiency of the artificial lung circuit and the infusion/drainage cannulae, and allowing use of cannulae having a reduced inner diameter compared to conventional cannulae. The device of the present disclosure provides an even blood flow pattern, preventing or reducing incidence of thrombosis. In turn, the presently disclosed design simplifies the blood circuit and also provides a pulsatile blood flow pattern, promoting active blood mixing and thereby improving gas exchange within the pump. The present device finds use at least in treatment of acute or chronic lung failure, as well as for combined right heart and lung (RVAD) failure.